The increase in world trade has largely contributed to the enormous growth in sea traffic. As a result, the market demand is leading to Ultra Large Container Ships ('ULCS'). These have a capacity up to 14 000 TEU, lengths up to 400 meters and similar operational requirements (speed around 27 knots).
The structural design of such ULCS container ships, with open midship sections, will result in an increased sensitivity to torsional and horizontal bending loads. At the same time, due to larger dimensions, the structural natural frequencies of ULCS become significantly lower. Thus, hydro elastic structural responses (springing & whipping) can become a critical issue in ship design and should be properly modelled by simulation tools.
However, it appears that existing simulation tools do not provide the definite answer to all these design issues. There is a clear need for their improvement. The importance of whipping and the insufficient knowledge in its modelling, is clearly reflected in the recent MAIB (Marine Accident Investigation Branch) report, following the loss of the MSC Napoli container ship.
The goal of the TULCS project was to deliver clearly validated design tools and guidelines, capable of analysing all hydro-structure interaction problems relevant to ULCS.
It is likely that the hull of the MSC Napoli was subjected to additional loads due to whipping. Furthermore, it is apparent that the whipping effect is currently very difficult to calculate or model in a reliable way.
In view of the potential increase in wave loading due to whipping effect, further research is required to ensure that the effect is adequately accounted for in ship design and structural analyses, and that sufficient allowance is made for the effect when determining design margins. The final goal of the project is to deliver clearly validated design tools and guidelines, capable of analysing all hydro-structure interaction problems relevant to ULCS.